Air ventilation systems consist of exhaust air ducts that are used to extract air from rooms and supply air ducts that are used to supply air to rooms. Air circulation between the supply air ducts and the exhaust air ducts via rooms is achieved either naturally or mechanically. Nowadays air circulation in buildings is usually achieved with Air Handling Units (AHU) that contain fans, heating or cooling elements, air filter racks or chambers, sound attenuators, and dampers. Air handling units are usually located on rooftops and they are connected to the exhaust air ducts and supply air ducts. The supply air ducts cannot be simply connected to room space via large uncovered openings because such large openings would lead to non-uniform air flow and draught which is unpleasant and harmful for occupants in the room space. Air distribution devices are used to distribute air uniformly in the room space. Air distribution devices are connected to air outlet ducts and usually comprise an array of openings arranged between the air outlet duct and the room space.
In displacement ventilation systems supply air from air outlet ducts is supplied at floor level close to occupants and air is extracted to the exhaust air ducts via outlets located above occupied zone, for example, at ceiling height. Heated air rises upwards due to its lower density and is collected via the outlets to the exhaust air ducts. The benefit of displacement ventilation systems is superior indoor air quality because supply air does not mix with contaminated heated air as much as in solutions where supply air distribution is arranged centrally or above occupants. Heated air becomes contaminated due to contamination sources such as electronic systems, electrical systems and occupants.
The challenge in the air distribution is most often to distribute air as uniformly as possible to a room without generating too much noise. This is especially important in the design of displacement ventilation systems where low-velocity air distribution devices are placed near the occupants.
Problems in prior art air distribution devices include non-uniform air distribution and unacceptable noise levels.
Therefore, it would be beneficial to have a solution which avoids the disadvantages of the prior art and where an air distribution device provides a uniform air distribution of supply air with reduced noise levels.